I. Field of the Invention
The present invention relates to a valve actuator and, more particularly, to a valve actuator for use with a valve having a rotatable member, the rotation of which actuates the valve.
II. Description of the Prior Art
There are a plurality of previously known valve actuators for use in conjunction with a valve having a rotatable member the rotation of which actuates the valve. For example, such valve actuators are typically used for valves on oil pipe lines or the like.
With such valves, a relatively great amount of torque must be applied to the valve rotatable member in order to initiate the opening of, or to "break", the valve. The additional torque necessary to break the valve results from encrusted deposits on the valve members and also from the natural compressive forces present at the complete opening or closure of the valve.
Heretofore, in order to generate a torque sufficient to break the valve, very large diameter handwheels have been secured to the valve actuator. While these previously known large diameter handwheels are adequate to break and actuate the valve, they are undesirable for a number of reasons.
One disadvantage of these previously known handwheels is that such handwheels are necessarily expensive to manufacture and involve high material costs due to their size.
A still further disadvantage of these previously known handwheels is that such handwheels are bulky and cumbersome to transport and handle, particularly when a single handwheel is intended to be sequentially attached to a plurality of different valve actuators.